Video: Refining a key

As I'm sure most of you know, once you pull your initial key of green screen or a blue screen, there's plenty more work left to be done to actually get that key acceptable and have a finished polished project. So if we look at our project here, you'll notice we have our QuickTime file, which, let's play it back. You can see it's a dancer here, and she was shot on green screen, and there is a key filter applied to it. Let's select the filter and look in the Inspector and you can see it's the Keyer.

Learn how to create stunning motion graphics and animations for video production. Author Ian Robinson explains how to format and animate type with the Transform Glyph tool and explores Motion's real-time 3D tools. The course also covers working in 3D space, creating depth with lights and shadows, keying green screen effects, and working with particle systems. In addition, Ian offers practical advice on integrating Motion into a professional video workflow and explains how to work smarter using rigs and templates.

Refining a key

As I'm sure most of you know, once you pull your initial key of green screen or ablue screen, there's plenty more work left to be done to actually get that keyacceptable and have a finished polished project.So if we look at our project here, you'll notice we have our QuickTime file,which, let's play it back.You can see it's a dancer here, and she was shot on green screen, and there is akey filter applied to it.Let's select the filter and look in the Inspector and you can see it's the Keyer.

And the Keyer is kind of interesting in that it automatically analyzes the imageand determines exactly what color to key out.Now if we look at the original image by clicking on the right thumbnail in theView section, you'll notice, yes, it is a green-screen shot, and the defaultsetting for this filter did automatically key out the green.Now, as you can see with our hair here, there are some white pixels around theedge, and a lot of times as I'm making adjustments to a key, yes, I like to keepmotion moving in real time, but also sometimes I like to actually park on aframe where I can see some specific issues, so as I make adjustments, we'll seeexactly what's happening.

Now, if you're joining me from the last video, Fill Holes, Edge Distance, andSpill Level might be familiar, but let me just recap really quick.The Fill Holes starts filling in the tiny holes of a key to try and fix anyareas that may have accidentally been keyed out that shouldn't have been.Now, this image I think looks pretty good the way it is, so I am going to leave it alone.Now, Edge Distance just determines how close to the edge this Fill Holes commandwill actually fill in.Now, the one I want you to pay attention to here is Spill Level.

If I drag this back to the left here, you'll notice there's a fair amount ofgreen that's already in this image.Now, this happens pretty naturally when you shoot green screen; especially ifsomebody is standing a little too close to the background of the green screen,you'll get a lot of reflection on their skin tones.Now thankfully, this was shot really well, so we have minor, minor things to deal with.What you want to do is drag this Spill Level up and to the right until it getsrid of the green, but you don't want it to unnecessarily start pulling anythingelse out from the image.

Invert just literally inverts the key that we have, so it's now keying out heractual body as opposed to the background.Now let's look in the Advanced section.If you open the disclosure triangle, there are two main sections:Scrub Boxes and Manual.And typically when you work in the Advanced area, you want to start with makingadjustments to your Scrub Boxes, and if you decide you want to go to the Manualarea, do so, but don't go back and make more adjustments to the Scrub Boxes.

Now, if we look at this wheel here, this box is showing me the main sampling ofgreen pixels that were used to determine this actual initial key.Now, if you click on one edge or the other, you can increase the amount of areathat's actually been keyed, and notice as I drag this, you can see right aroundthe edges here it's actually starting to pull a little bit more of the image androlling the edges of that mat in.It's a very, very subtle adjustment, but basically we're increasing the amountof variance to the left of that image.

If you decide you want a wider initial selection, you need to go back up and useRefine Key to manually set the amount of selections.Now, if you're unfamiliar with how to do that, jump to the previous video--I covered that pretty well in there.Now, Manual just gives me a manual control over the sliders for the amount ofluma that we're adjusting with the key.In this example, I don't need to use Manual, so let's just go back to our Scrub Boxes here.

I want you to understand Rolloff.We have two settings:there is the Chroma Rolloff and the Luma Rolloff.Now, whenever a key is pulled, it's a combination between the actual chrominancevalue, which is the color saturation of the image itself, and then there is theLuma Rolloff, and the luma is the brightness of that color.So as we're making adjustments to the Rolloff, notice it is kind of adjustingthe edges as well as how much of that image is being keyed, based on thechrominance or the luminance.

So this just gives you a little bit more finite control over exactly where theimage is getting keyed and how much of it is getting keyed and how soft thattransition is actually happening.See, as I adjust the Luminance Rolloff, notice here in the Luma graph, the edgeof this curve is getting more and more sharp.As it gets more sharp, the sharper the transition from the key to the keyed-outareas are going to be.So it's going to create a more jagged look to the mask.

So I'll just bring my Luminance Rolloff back over here to the left.We'll leave these values around 25 and 29 accordingly.Now we've covered the primary areas of the Keyer that deal with actually pullingthe key, selecting the colors we're going to pull, and knocking that out.Now, the next area here is the Matte tools.Now, the Matte tools adjust the matte that's actually generated from the key.But it is separate.We're not actually adjusting any of the parameters that have to do with thecolor or its saturation.

We're literally just adjusting this matte.So one of the most common things to adjust is Shrink/Expand.If I drag to the left, it's going to shrink the mask.If I drag to the right, it's going to expand our selection here.So typically you want to have something in the middle.If anything, probably roll it back a little bit.When I did that, notice I've made these harsh edges.So you can adjust that by adjusting the Soften command as well as the Erode command.Now, Erode is kind of different than softness in that it adjusts how thetransparency increases from the solid portion of the key inward.

Usually what I like to do is use the "if it looks good it is good" and just kindof click and drag to adjust the Softness and the Erode settings.Now, it's really important as you make these adjustments to kind of bounce backand forth between viewing the matte and the composite of our key.So I'll leave my settings set like this for now, but a lot of times whatyou'll end up doing is adjusting one thing, going and adjusting the nextthing, and then coming back.So we will come back to the Matte tools here in a second.I want you to look at Spill Suppression.

This is a separate, slightly more refined option for adjusting the Spill controls.Notice up here we had our Spill Levels in the top of our key section in theKeyer, but now we have Spill Contrast here, which helps you adjust a couple of things:Tint, which mixes in the color values of the original image, and the Saturation,which is obviously how saturated that mix is going to be.Now, you can adjust the Contrast as far as how much contrast there is betweenthe actual spilled image and its adjusted counterpart.

So notice as I click here on the white and adjust the Contrast, it's taking thewhite areas of the spill and kind of crushing out the green in there.Now, I know I don't want to make any adjustments in my Spill Contrast, so I'llreset that back to its original settings.A lot of times I found my most success by adjusting the Light Wrap.This is kind of cool. Light Wrap analyzes the background video and mixes that in around the edgesof our keyed footage.

This works extraordinarily well if you're actually trying to mix in the footageover background video, as opposed to something like this, a solid color.So if we go to our file browser here, we can navigate in our exercise files, inthe Media folder, under Footage, for green screen.Here we have some background video footage.Now, I want to go ahead and superimpose her on the sidewalk.So we can drag and drop the sidewalk video footage right above ourbackground red video here.

And now let's go to the Inspector, make sure we have our Keyer selected, and inthe Filter selection go down under Light Wrap.Now, just crank up the amount of Light Wrap in the image and see what starts to happen.Notice we crank this all the way up to 50.We get a very soft look that's moving into the scene.But if you notice it's actually blending in different colors and areas of thescene back into our keyed footage.Now, obviously this amount is a little much, so I'll bring it down to around 16.But we can also adjust the Intensity as well as the Opacity of this mixture.

So you can really get a nice fine adjustment.Notice as I drag the intensity down to the left, I'm getting rid of some ofthe issues that I had with the white pixels around the edges of her hair andthe edges of her face.That's because the intensity adjusts the gamma levels to the lightened ordarkened sections of the wrapped edge values around the foreground image.You can even adjust the blend mode, but for now I like how this is looking so far.

Now, remember how I said we would jump back up to our Matte tools?I want to do that because I'm still getting this white halo around the hair, andif we drag on the right side of the image here, notice it's introducing morewhite into the image, which is not what I want to do.So I'll leave the white area set up and reset the black point here, and younotice now as I do that what it's doing is it's crushing out the black levels ofthe matte that's been created.

So if we look at our matte object here, notice as I drag this left andright, it's kind of hard to see, but you can see it more here along the edges of our logo.What it's doing, it's taking anything that's gray and making it more and more black.Now, what this is also doing is allowing me to kind of cut out some of thoseproblem areas in the edges of her hair.And if we adjust the gray levels, it's also going to make an adjustment.Let's go ahead and drag that up to the right, and here you notice now I'mstarting to get rid of some of that white along the edge of her hair.

So now that I've adjusted the matte and gone through all of the differentadjustments within the Advanced options for the Keyer, the only thing that'sreally left to do is actually match back the color of the image and deal withcreating a holdout mask.So that pretty much wraps up our quick tour of the Advanced options forthe Keyer.

Learn by watching, listening, and doing, Exercise files are the same files the author uses in the course, so you can download them and follow along Premium memberships include access to all exercise files in the library.

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Learn by watching, listening, and doing! Exercise files are the same files the author uses in the course, so you can download them and follow along. Exercise files are available with all Premium memberships.
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